Car radio possessed??

[leenowell]

Hi All,

I replaced the radio in my 2001 Ford Focus a few years ago and it has been fine until a few weeks ago. All of a sudden, all sound will go but otherwi se the radio/ CD seems to be functioning fine. Almost as if it has been mu ted.

Thinking there was a loose connection somewhere, I took the radio out today and although there was no sign of a loose connection, I did notice the fol lowing very odd behaviour..

The car's wiring harness seems to have 2 connectors for the radio these are connected via an wiring converter I bought at the time to the radio. The yellow connector appears to be the speaker connector. Now the odd bit...

With the radio on and no sound to the speakers, if I disconnect the yellow connector and reconnect it, the sound returns to normal. Oddly if I then sw itch from radio to CD, it goes silent again until I disconnect and reconnec t the yellow connector and it springs back to life again....

The only other info I have is that the car has one of those old fashioned i n car kits fitted when I bought it. The type when you put the phone in the cradle and it has a microphone and speaker to enable you to take calls. T he reason I mention this is that I wonder if this is something to do with i t that it is somehow muting the speakers as if a call were in progress or s omething... Maybe grasping at straws :)

Anyone have an idea about what is going on??

thanks

Lee.

[Brian-Gaff]

Hard to say without more details on this adaptor for the phone. also the best thing would be to actually see if the output is there with a bare bones system which of course involves running said radio out of the car completely so you can monitor the signals in and out of the device. Brian

[Harry Bloomfield]

[e-mail] explained :

A Cark will mute the radio during a call, so removing that would be a good starting point, if you do not use it. Most often car ICE systems include a mute duing a call connection and if you can work out which one that is, you could just disconnect that.

[bert]

In article , Harry Bloomfield writes

It's usually yellow!!

[leenowell]

Hi all

I have now ripped out the phone system and still no joy. As far as I could tell, the connector on the phone side had a yellow lead which was cut comin g out of the connector which goes into the phone gadget. Ie not connected t o anything although in theory could have shorted. On the radio side, I beli eve the phone mute wire is brown coming out of the radio. This connector is then in turn connected to the normal car wiring. At this connection, there doesn't appear to be anything connected to the brown wire. So... All in al l I can't see a way of this being the issue.

Unfortunately, I don't have a spare radio to check to see if it is the radi o. Is there any other test I can do to be sure before I buy as new one? Eg would the brown lead be +12v or something?

Thanks in advance

Lee.

[leenowell]

Hi All,

The problem has now been solved but I was wondering if anyone could explain how it caused the symptoms I experienced.

Much to the amusement of the family, we discovered purely by accident that when one of the rear doors was open sound came out of the speakers as norma l. When closed, no sound out of any speakers. I took the door apart and t he speaker was held on by one screw and this had come loose. Net result wa s the speaker was moving back and forth as the door was opening and closing . I assumed it was because the speaker needed to be electrically connected to the car and hence the problem. However it seemed to work fine even with the speaker in my hand... Anyway, tightening the screw up seems to have f ixed the problem.

Does this make sense to anyone or maybe the root cause was something else a nd I have made a temp fix?

thanks

Lee.

[Adrian]

Fractured wire.

[Adrian Caspersz]

I suspect one of the speaker wires is intermittently shorting to the chassis.

[The Natural Philosopher]

maybe it was shorting out and shutting the amp down completely

[Brian Gaff]

Hmm, well to me this sounds like you may well have a fracture somewhere in the wire that is common perhaps to all the speakers? Ground as you say but I'd not expect them to use the car itself for a speaker, indeed many car radios do not have one side of the speakers grounded as they operate two amps in a bridge formation to get more output on the low voltage. However some more modern ones use an inverter to get nearer 40 volts which can be more useful.

Lets hope the culprit shows itself soon. I cannot imagine a fault condition that would cut all speakers unless there was a dead short and the power supply turns off the juice to save the transistors. Brian

[leenowell]

Unless the car has a separate amp installed by default, my setup is just a simple (cheap) CD radio (about 5 years old). I removed the standard factory fitted double height radio and replaced it with this one using some adapter leads from Halfords.

In terms of power to the radio, the device behaves identically when there is no sound as it does when it has sound. i.e. has power, you can play a CD (obviously without sound!) etc.

All very odd.

[Dave Plowman (News)]

Only logical conclusion is a short on the speaker wiring when the door was closed. Although I'd have expected a decent unit to only shut down one channel - assuming it is stereo.